Capturing and Sequestering CO2 from a Coal-fired Power Plant - Assessing the Net Energy and Greenhouse Gas Emissions

It is technically feasible to capture CO2 from the flue gas of a coal-fired power plant and various researchers are working to understand the fate of sequestered CO2 and its long term environmental effects. Sequestering CO2 significantly reduces the CO2 emissions from the power plant itself, but this is not the total picture. CO2 capture and sequestration consumes additional energy, thus lowering the plant’s fuel to electricity efficiency. To compensate for this, more fossil fuel must be procured and consumed to produce extra electricity. Taking this into consideration, it was desired to determine what the actual reduction in global warming potential (GWP) would be to maintain power generation capacity. To answer this, an analysis was performed at the National Renewable Energy Laboratory to examine the GWP and energy balance of coal-fired power generation which incorporates CO2 capture and sequestration. To understand the overall environmental implications, a life cycle approach, which takes into account the upstream process steps, was applied. The reference system consisted of coal mining, transportation, and power plant operation. In order to maintain power generation capacity, additional capacity must come from another source. Two sources were examined: extra capacity from a natural gas combined-cycle system or extra capacity from the grid.